Method of making a slide-fastener coupling element

ABSTRACT

A method of making a slide-fastener coupling element from a synthetic-resin monofilament which comprises deforming the monofilament at spaced locations to provide a pair of shank bulges on opposite sides and spaced from each coupling-head bulge and coiling the monofilament to produce a multiplicity of turns each with a coupling head whose projections extend laterally of the plane of the turns and whose bulges are set back from the coupling units and are juxtaposed so that an eye is defined by each turn for receiving the coupling-head projection of the turn of another coupling element. Hence the two bulges of each turn flank the coupling head of the turn of an opposing coupling element, while each coupling head is flanked by the two bulges of a mating turn.

United States Patent [151 3,705,229 Heimberger [45] Dec. 5, 1972 [5 METHOD OF MAKING A SLIDE- ExamineF-Robeft white [72] Inventor: Helmut Heimberger, Grenzach,

Germany [73] Assignee: Opti-Halding AG, Glarus, Switzerland [22] Filed: Apr. 29,1970

[2]] Appl. No.: 33,031

[52] US. Cl ..264/28l, 264/284 [51] Int. Cl. ..B29d 5/00 [58] Field of Search ..264/281; 18/ 19 C, 1 Z

[56] References Cited UNITED STATES PATENTS 3,197,537 7/1965 Hansen ..l8/l9 3,137,037 6/1964 Wilcken ..18/19 3,445,560 5/1969 Steingruebner ..264/28l 3,069,723 12/1962 Porepp ..l8/1

FASTENER COUPLING ELEMENT Assistant Examiner-Richard R. Kucia Att0rney-Karl F. Ross 57 ABSTRACT A method of making a slide-fastener coupling element from a synthetic-resin monofilament which comprises deforming the monofilament at spaced locations to provide a pair of shank bulges on opposite sides and spaced from each coupling-head bulge and coiling the monofilament to produce a multiplicity of turns each with a coupling head whose projections extend laterally of the plane of the turns and whose bulges are set back from the coupling units and are juxtaposed so that an eye is defined by each turn for receiving the coupling-head projection of the turn of another coupling element. Hence the two bulges of each turn flank the coupling head of the turn of an opposing coupling element, while each coupling head is flanked by the two bulges of a mating turn.

5 Claims, 4 Drawing Figures PATENTEU DEB 5 I97? 3. 7 O5 2 2 9 sum 1 or 2 I F l G i HELMUT HEIMBERGER INVENTOR.

ATTORNEY PATENTED'HEB 5 i972 SHEET 2 OF 2 HELMUT HEIMBERGER INVENTOR.

Karl

ATTQRNEY METHOD OF MAKING A SLIDE-FASTENER COUPLING ELEMENT 1. Field of the Invention The present invention relates to slide-fastener stringers and, more particularly, to an improved coupling element and method of making same.

2. Background of the Invention Coupling elements for slide-fastener stringers have been provided heretoforein numerous constructions and by a number of techniques. For example, it is known to forming coupling elements of slide-fastener stringers from a multiplicity of spaced apart coupling members form a coupling chain and individually mounted upon the support or carrier tape, band or strip.

For no-snag or snag-free purposes, however,

continuous coupling element chains have recently come to the fore. Such coupling elements comprise an undulating or meandering synthetic-resin monofilament which may be deformed at each undulation to form a coupling head receivable between the coupling mating slide-fastener half. Alternatively, the coupling element may be a continuous monofilament coiled into a general helical strip, each turn of the coupling elements interfitting between the heads of the coupling element of a mating slide-fastener half. It is with coupling elements of the latter type, i.e., generally helical monofilament coupling elements, with which the present invention is concerned.

For the most part, coupling elements of the helicoidal or coil type, comprise a multiplicity of identical turns interconnected at the tape side (rear side) of the coupling element, by bights of the monofilament which loop from one turn to another. Each turn is formed, at the opposite side (coupling side) of the coupling element, with a respective head engageable between the heads of the opposed coupling element. The head may be bulges deformed upon the syntheticresin monofilament, which may be composed of molecularly oriented nylon-type polyamide or polyester synthetic resin.

For the most part, the resistance to opening of the coupling element depends upon the shape and dimensions of the coupling heads which interfit between one another when a slider is shifted in the closing direction along the stringer. The head is formed at the junction of a pair of shanks, one of which connects the head to the bight of a preceding turn, while the other is connected between the bight of the succeeding turn and its head. The heads are formed by deforming the monofilarnent which may be of circular or slightly ellip tical cross-section.

It has been noted that the security of the slidefastener, equipped with coupling elements of the described type, depends to a significant degree upon the dimensions of the coupling heads, i.e., to the extent the matingly interconnected coupling elements transversely to the plane of the stringer and to the longitudinal axis of the coupling elements. If, for example, the coupling heads are not received between the shanks of the opposed coupling element but merely are locked behind the coupling heads of of the latter, such transverse forces readily separate the coupling elements. While a solution to this problem might appear to be the simple expedient of enlarging the coupling heads, this cannot always be done with ease since the extent to which the synthetic-resin monofilament can be deformed without substantial weakening is limited. This difficulty will be all the more appreciated when it is understood that the gap between the turns of the coupling element, to satisfactorily accommodate the opposing heads, must exceed the diameter d by the increment say of, d/lO if smooth operation of the slider heads of an opposed coupling element carried-by the and a operation fit is to be obtained.

The projecting portions of each turn must, therefore, extend laterally by somewhat more than this increment and conventional deformations of small-diameter monofilaments (e.g., less than 1 mm diameter) of the character described seldom can accommodate such deformation without significant weakening of the monofilament itself. Hence prior-art systems have been compromises between weakening of the turns at the coupling heads, at which most stress is applied, the security of the interengagement of the coupling elements, and the resistance to transverse stress.

OBJECTS OF THE INVENTION It is, therefore, the principal object of the present invention to provide an improved method of making a coupling element of greater ability to resist stress of the type described and free from the weakening characteristics of prior-art coupling elements.

SUMMARY OF THE INVENTION It has now been found that it is possible to overcome the aforementioned disadvantages by providing each turn of a generally helical coupling element of the general character described, i.e., composed of a monofilarnent, with a coupling head having lateral protrusions or projections (projections extending transversely to the plane of the coupling turn but in the direction of the axis of the coupling element itself), while the shanks of the turn are formed with lateral bulges rearwardly of the heads. Hence the lateral protrusion of the coupling head is received between the corresponding upper shanks and the corresponding lower shanks of adjacent turns of the opposing coupling element at locations in which the bulges of the shanks of these turns reach toward one another and thereby close the gap between the turns to a small fraction of the intergap space in the absence of such bulges. Consequently, the intermediate bulges of the shanks and the heads of the mating coupling element interengage or overlap so that a diminished deformation of the coupling head is possible'without materially reducing the resistance of the slide fastener to transverse stress or the resistance of the slide fastener to such transverse stress is increased for a given deformation of the coupling heads.

The two shanks of each turn of the coupling element, referred to hereinas the upper and lower shanks, are

connected with the adjacent turns preceding and following the turn in question, by respective bights as discussed earlier. The bulges and the head projections are formed, in accordance with a particular feature of this invention, by plastic embossment of the synthetic- 'resin monofilament and at least the head is shaped in part by kinking the turn of the coupling element at the head so that the shanks of the respective turn diverge away from the head at an appropriate angle. As a result each turn, in projection in a plane perpendicular to the coil axis, has a projection with a configuration of an eye in which the head of the opposing coupling element can engage.

According to still another feature of the invention, the generally elliptical eyes of the turns are dimensioned to receive the lateral projections of the heads while obstructing further inward movement of the opposing head beyond the region defined by the shank bulges while the shank bulges themselves limit inward movement of the knees'of the shanks formed at these bulges at the junctions between the rearwardly divergent shank portions and the rearwardly converging shank portions leading from the shank bulges to the respective bights. Hence the interfitting heads, according to the present invention, substantially overlap when considered in projection in a plane perpendicular to the slide fastener plane. The divergence of the shanks from the slide-fastener plane in the direction of the axis of the coupling element is, in the case of the coupling element composed of a synthetic-resin mono-filament with a diameter of 0.5 mm, about According to the principles of the present invention, the shank bulges are hot-pressed in the synthetic-resin monofilament and have a transverse width (d/2) half the diameter (d) of the monofilament wider than the monofilament while the coupling heads have at least equal width and preferably are still a quarter of the diameter of the monofilament (511/4) wider. According to the invention, therefore, the bulges for the heads and the shanks are pressed into a synthetic-resin monofilament without penetrating deformation and the additional spread of the head is obtained by a penetrating deformation or embossment.

Furthermore, the length (along the monofilament) of which the shank bulges in the direction perpendicular to the axis of the coupling element is greater than the corresponding length of the coupling head and neither is as large as the gap between them. The system of the present invention provides a surprising flexibility in the slide fastener, accompanied by greater transversestress resistance and resistance to damage of the coupling heads than heretofore.

DESCRIPTION OF THE DRAWING The above and other objects, features and advantages of the present invention will become more readily apparent from the following description, reference being made to the accompanying drawing in which:

FIG. 1 is a greatly enlarged fragmentary plan view of two coupling elements as made in accordance with the present invention, in an interconnected configuration;

FIG. 2 is a cross section of the system of FIG. 1 taken along the line IIII of FIG. 1;

FIG. 3 is an elevational view of a portion of the coupling element monofilament prior to coiling; and

FIG. 4 is a view similar to FIG. 2 illustrating another embodiment of the invention.

SPECIFIC DESCRIPTION In the drawing, the generally helical coupling elements A and B are complementary but of otherwise similar construction so that the present method will be described in connection with only one of the coupling elements. The axis of the coupling element A is represented at 18 and corresponds to the direction of movement of the slider along the coupling elements. In the system of FIGS. 13, each turn T of each coupling element comprises a coupling head 3, a pair of shanks 1 and 2 extending rearwardly from the head and a pair of bights 4 connecting the shanks 1 and 2 with the adjacent turns. The axes of the shanks 1 and 2 are represented at 7 and define a plane perpendicular to the plane of the paper in FIG. 1 and to the axis 10. The plane of the paper in FIG. 1 may represent the slidefastener plane for the purpose of the description.

As best seen'in FIG. 2, each turn defines a generally elliptical eye 5 in projection on a plane perpendicular to the stringer plane, as determined by a pair of forward shank portions la, 2a which diverge outwardly from the head 3 at an angle awhich is exaggerated in the drawing and may range from 5 to 40 and preferably is about 10 in the case of a monofilament of diameter d 0.5 mm) in the region of the inner surfaces of these shank portions as represented at B, The rearwardly divergent shank portions 1a and 2a form knees 1b and 2b at their respective junctions with the rearwardly convergent shank portions 1c and 1d of similar inclination.

As illustrated in FIG. 3, the synthetic-resin monofilament originally may have the diameter d 0.5. mm)

. and may be a smooth-surfaced strand which is embossed by pressing the strand under heat against'a flat surface represented by the plane of the paper in FIG. 3. For each turn, these deformations include a pair of bulges 6 of transverse width greater than or equal to 0.5d on either side of the axis of the monofilament such that the overall width w of the deformed or flattened portion exceeds the diameter d and, preferably w 2 d.

The coupling head, however, is generally diamond shaped, whereas the bulges 6 are rounded, and have lateral projections 3a and 3b extending along the longitudinal head axis 3c which runs transversely to the axis 7 and, in the coil coupling element, perpendicular to the plane of the respective turn. In accordance with the present invention, the head 3 is firstly formed to a rounded bulge 30 by pressing as described for the bulge 6 and is of substantially the same configuration. Thereafter, penetrating embossment in the region 3d by a diamond-shaped tool, whose diagonals lie along the axis 7 and 3c in FIG. 3, is used to extend the projections 3a and 3b to their full dimensions as illustrated in this Figure. The overall width w of the head 3 in the longitudinal direction of the coupling element and transversely to the plane of the respective turn is about a d/4 greater than the bulges 6. Hence W may be equal to 2.5d. In coiling the deformed strand, the coupling head 3 may be kinked along the line 30 and the embossment 3d located internally or externally. The converging portions 1c and 1d defining the rearward half of the eye 5, narrow in the region behind the bulges 6 such that further leftward displacement of the turns of the right-hand coupling element beyond that shown in FIG. 2 is limited and the coupling heads 3 are received in the eye 5. In the projection perpendicular to the plane of the slide fastener and to the axis 10, see FIG. 2, the shank portions la and 2a of the mating coupling elements overlap. Preferably, such overlapping extends beyond the bulges 6 and almost to the bight portions 4.

In the embodiment of FIG. 4, the knee portions lb and 2b are embossed inwardly with respect to the eye and form the bulges 6. In the cases of the system of FIG. 2, the force is applied in the direction of the arrow f, i.e., outwardly. In either case, the deformation is effected in the uncoiled condition of the strand against a flat surface and the axial length of the heads 3 is made relatively small, i.e., smaller than that of the bulges.

I claim:

1. A method of making a continuous helical coupling element engageable with a mating coupling element in a slide fastener upon movement of a slider along said coupling elements, the coupling element having a multiplicity of similar turns of a synthetic-resin monofilament, each turn having a given length of the monofilament and being formed with a head centrally along the the respective length while each length is connected at its ends with the lengths of monofilament forming an adjacent turn by respective bights, said method comprising the steps of:

deforming each of said lengths of a continuous monofilament on opposite sides of the site of the respective head to form a pair of lateral bulges for each turn spaced on opposite sides of each site; deforming each of said lengths of said monofilament at the respective side to provide a pair of diametri 6 cally opposite lateral projections at the respective hand;

thereaftercoiling the monofilament in a generally flattened helix to shape each length into a generally elliptical eye at least in part by bucking said turns at said sites whereby said lengths form shanks reaching rearwardly from the-respective head and coplanar for each eye with said bulges flanking the openings of each eye inwardly of the respective head and accommodating between them a projection of a mating head receivable between a pair of such turns; and

penetratingly embossing each of said heads to plastically deform said projections further from the outline of the original synthetic-resin monofilament than said bulges.

2. The method defined in claim 1 wherein said bulges each have a width transversely of said monofilament equal approximately to half the diameter thereof and said projections have a width transverse to said monofilament of about a quarter of the diameter of said monofilament greater than said bulges.

3. The method defined in claim 2 wherein said head is generally diamond shaped and is formed by the impressing of a diamond-shaped tool into said monofilament 4. The method defined in claim 3 wherein said shanks are bent inwardly around the penetrating embossment.

5. The method defined in claim 3 wherein said shanks are bent outwardly away from the penetrating embossment. 

1. A method of making a continuous helical coupling element engageable with a mating coupling element in a slide fastener upon movement of a slider along said coupling elements, the coupling element having a multiplicity of similar turns of a synthetic-resin monofilament, each turn having a given length of the monofilament and being formed with a head centrally along the the respective length while each lengTh is connected at its ends with the lengths of monofilament forming an adjacent turn by respective bights, said method comprising the steps of: deforming each of said lengths of a continuous monofilament on opposite sides of the site of the respective head to form a pair of lateral bulges for each turn spaced on opposite sides of each site; deforming each of said lengths of said monofilament at the respective side to provide a pair of diametrically opposite lateral projections at the respective hand; thereafter coiling the monofilament in a generally flattened helix to shape each length into a generally elliptical eye at least in part by bucking said turns at said sites whereby said lengths form shanks reaching rearwardly from the respective head and coplanar for each eye with said bulges flanking the openings of each eye inwardly of the respective head and accommodating between them a projection of a mating head receivable between a pair of such turns; and penetratingly embossing each of said heads to plastically deform said projections further from the outline of the original synthetic-resin monofilament than said bulges.
 2. The method defined in claim 1 wherein said bulges each have a width transversely of said monofilament equal approximately to half the diameter thereof and said projections have a width transverse to said monofilament of about a quarter of the diameter of said monofilament greater than said bulges.
 3. The method defined in claim 2 wherein said head is generally diamond shaped and is formed by the impressing of a diamond-shaped tool into said monofilament
 4. The method defined in claim 3 wherein said shanks are bent inwardly around the penetrating embossment.
 5. The method defined in claim 3 wherein said shanks are bent outwardly away from the penetrating embossment. 